Modeling of SPERT IV Reactivity Initiated Transient Tests in EUREKA-2/RR Code

EUREKA-2/RR code has been used for SPERT IV reactor benchmark calculations against the experimental results provided by IAEA (International Atomic Energy Agency) obtained for a series of transient tests initiated by step insertion of different magnitudes of positive reactivity with varying degrees of different controlled parameters such as reactor initial power, coolant temperature and coolant flow condition. 20 out of 39 tests that fall under forced convection mode have been considered for the present simulation provided the reactor scram system is disabled. Peak power and peak clad temperature due to transient have been calculated and it was found that although peak clad temperature values agreed, the peak power values seem to underestimate the experimental values. Further study appears to be needed to identify the limitations in modeling or examining the effect of input parameters during modeling to obtain the better simulation results. 1. Introduction Since SPERT program initiated in 1954, a variety of configurations under a broad range of conditions have been taken into consideration to study transient behavior of nuclear reactors. With the growing need to validate the experimental results, numerical code has got much attention and PARET is one such computer code originally developed for the analysis of SPERT-III experiments in 1969 [1]. Later, this code has been modified incorporating many issues such as selection of flow instability, departure from nucleate boiling, single- and two-phase heat transfer correlations, and a properties library considered more applicable to the low pressures, temperature, and flow rates that enhances the acceptability of the code for its subsequent use in the analysis of transient behavior of research reactor. However, in modeling the research reactor transient condition, the analyst has to consider some conservative assumptions due to lack of experimental data which may lead to false prediction of the real physical phenomenon that takes place in the reactor. One common point that came out from reactor analysis is the importance of proper selection of input parameters such as DNB correlations to obtain the real characteristic of the transient parameters [2, 3]. In this context, reactivity initiated transient analysis code EUREKA-2/RR [4] has been used whether it could be able to model the SPERT IV transient experiment. This work has been done under the framework of the International Atomic Energy Agency Coordinated Research Project (CRP) 1496 “Innovative Methods in Research Reactor Analysis: Benchmark Against